Alexander's successors: The Third Diadoch War

Diadochi
('successors'): name of the first generation of military and political
leaders after the death of the Macedonian
king and conqueror Alexander
the Great in 323. To settle the question whether his empire should
disintegrate or survive as a unity, and, if so, under whose rule, they
fought four full-scale wars. The result, reached by 300, was a division
into three large parts, which more or less coincided with Alexander's possessions
in Europe, Asia, and Egypt.

During the next quarter of a century, it was decided
whether these states could endure. As it turned out, there were no great
territorial changes, although there were dynastic changes. After 280, the
period of state-forming came to an end.

An overview of all articles on the Diadochi on
this website can be found here.

After the Second Diadoch War, Antigonus
Monophthalmus was sole ruler in the east, and the strongest of the
Diadochi. Ptolemy
was alarmed by the growth of his power, knowing that he would be unable
to retain the independence of Egypt against the united forces of Asia.
We have already seen that the conflict between Antigonus and Ptolemy was
not new (above).

The ruler of Egypt warned Cassander and Lysimachus,
the satrap of Thrace. In the autumn, the three men concluded an alliance
against Antigonus, and sent an ultimatum to Antigonus, which reached him
in the winter of 316: all money had to be redistributed and he had
to give up his conquests. Of course, the man who had in three years' time
conquered everything between the Aegean Sea and Iran, was unwilling to
give in. A new war broke out: the Third Diadoch War (spring 315).

Antigonus immediately seized the initiative. He invaded Syria to secure
Phoenicia with its naval resources, which were needed for anyone who had
to invade the Aegean world or Egypt. In the summer, he laid siege to Tyre,
which had become independent but was supported by Ptolemy (text). The defenders withstood their
enemies for a long time, which offered Seleucus,
who now served as Ptolemy's admiral, an opportunity to conquer Cyprus.
He continued to the Aegean Sea, where he visited Miletus and the oracle
of the Branchidae, which greeted him as 'king'.

At the same time, Antigonus demanded that Cassander explained what had
happened to Alexander's mother Olympias
(who had already been murdered), his wife Roxane
and his son, the young Alexander
(who had not been seen in public for some time). Of course, Antigonus allied
himself to Polyperchon, who still controlled part of the Peloponnese and
would prevent Cassander's crossing to Asia; and finally, Antigonus repeated
the proclamation that Polyperchon had made four years before: that the
Greeks were to be 'free and autonomous'. This was an extremely clever move,
because Ptolemy, who wanted to act as protector of Greece as well, was
now forced to guarantee its freedom as well, and thus act against Cassander's
wishes (text). Antigonus' final move against
the ruler of Macedonia
was the creation of a federation of the island states in the Aegean Sea,
which he could use when he attacked Cassander at home (the Nesiotic
League).

In November 315, the alliance with Polyperchon
paid off: the Peloponnese sided with Antigonus. Cassander was almost defeated
and opened negotiations. Before he could conclude a separate peace with
Antigonus, however, his allies Lysimachus and Ptolemy renewed their offer
of assistance, and Cassander decided to continue the struggle. When Antigonus
wanted to invade Europe, Lysimachus was ready for him, and Antigonus' attack
came to nothing.

In the meantime, Ptolemy was gathering his forces. Although Tyre had
fallen, he still had a large navy and decided to attack Cilicia
(summer
312). At Gaza, his army was
intercepted by Antigonus' son Demetrius
and his officers Peithon of Babylonia
and Nearchus,
who were unable to overcome the ruler of Egypt (autumn). Ptolemy proceeded
to Syria, but when Antigonus arrived, he returned home, knowing that his
forces were no match for the lord of Asia (winter 312/311).

At this moment, Antigonus made the greatest mistake of his life. One
of the commanders in Ptolemy's army was Seleucus, the former satrap of
Babylonia. While the forces of Ptolemy were retreating, he took his units
and instead of marching to Egypt, crossed the desert and advanced to Babylon,
where he was recognized as satrap on 1 June 311.
Although the consequences of this action were, at that time, unclear, Seleucus
turned out to be Antigonus' nemesis.

By now, it had become clear that Antigonus and Demetrius could not defeat
Ptolemy, Lysimachus, and Cassander in the near future. A peace treaty was
concluded in December. Ptolemy and Lysimachus were confirmed in their territories;
Cassander and Antigonus remained supreme commanders of the Macedonian forces
in Europe and Asia; the Greek towns were recognized by all parties as 'free
and autonomous' (but Cassander kept garrisons at several places); and it
was agreed that the boy king Alexander, son of Alexander the Great and
Roxane, would become sole ruler of the entire empire when he came of age,
in 305. The result of the treaty was, of course, that Roxane and the twelve
year old Alexander were killed. This was the end of the Macedonian royal
house. (The story is told here.)

In a letter to the Greek towns (text),
Antigonus explained why he had not continued the war. He did not want it
to last and wanted to put an end to the destruction of Greece. This was
less hypocritical than it may sound: Antigonus wanted the Greek towns as
allies, which was in the realm of the possible, and not as subjects, which
was impossible. Another motive was that he had now covered his back, and
could attack Seleucus, whom he had by now recognized as a dangerous enemy.